The body of a woman who went missing in floodwaters has been found as the flood crisis engulfs much of NSW.

Police say they have not formally established the identity of the woman, but believe it could be that of Diane Smith.

She was from the central western town of Eugowra, which was devastated by roof-high flash-flooding early on Monday.

Ms Smith, 60, last spoke to a relative on the phone from her car on Monday morning.

Ljubisa “Les” Vugec, 85, who was last seen at his Eugowra home around the same time, remains missing.

Ljubisa ‘Les’ Vugec and Diane Smith were reported missing after flash flooding at Eugowra. Photo: NSW Police

State Emergency Service chaplain Steve Hall said Eugowra had been decimated in the disaster.

“Everything they hold dear has been swept away in a wall of water,” he said.

Rescue helicopters, military personnel and international emergency crews continue to work across NSW flood zones as people in the central-western town of Forbes brace for their second inundation in a fortnight.

The Bureau of Meteorology said the Lachlan River at Forbes could meet the historic June 1952 peak of 10.8 metres on Wednesday, while major flooding was expected to persist until the end of the week.

Forbes Mayor Phyllis Miller estimated two-thirds of the town was already inundated, ahead of Wednesday’s likely peak.

“I’ve never seen a flood like this in my lifetime,” she told the ABC.

“It’s really hard on the people that have just experienced it two weeks ago.”

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Elsewhere, people in parts of the north-western town of Gunnedah and the central town of Gooloogong have been told to evacuate .

The Namoi River was predicted to peak near 8.2 metres on Wednesday morning.

In the 24 hours until Wednesday morning, the NSW SES responded to 329 calls for help and performed 17 flood rescues.

Emergency Services Minister Steph Cooke said there were 122 flood warnings across NSW, and hundreds of homes had been destroyed.

Local Nationals MP Andrew Gee said this week’s heavy rain had left “Lismore-level damage” in central NSW.

SES Chief Superintendent Dallas Burns said floodwaters at Forbes were slowly rising with water spreading throughout the town.

Fourteen people were rescued in Forbes about 8pm on Tuesday, after the Plainsman Motel was inundated.

A helicopter rescued an elderly couple, their daughter and two small dogs from a Forbes home that was threatened by rising waters about 10pm.

About 1000 people and up to 600 homes and businesses are affected by evacuation orders in the town.

Crews have been door-knocking and sandbagging after 120 millimetres of rain fell in a matter of hours early on Monday, causing ferocious flash flooding and forcing Wyangala Dam to spill into the swollen Lachlan River.

Labor’s water spokeswoman Rose Jackson said the government’s broken promise to raise the dam wall was disappointing for devastated communities.

“Wyangala Dam [raising]… is not funded in the budget,” she said.

“It was announced prior to the last election as a drought resilience project. Yet here we are, years later, with no work done.”

Labor’s flood mitigation plan did not include raising the dam wall, as it would only give false hope, Ms Jackson said.

“It’s really unfortunate that the NSW government has once again chosen to politicise water in this state and chosen to reignite dam wars when they have no intention in proceeding with this project,” she said.

Opposition Leader Chris Minns said Labor had a $200 million package to beef up evacuation routes and stop building on flood plains.

The torrential rain doubled the height of Mandagery Creek at Eugowra, east of Forbes, early on Monday, devastating the town of 800 people.

Eugowra residents have described two sudden and intense surges of water flowing through the town, washing away houses, knocking over structures and leaving destruction like a “war zone”.

-with AAP